1) Field of the Invention
The present invention relates to adhesive tapes which can be bonded to substrate members such as die pads of leadframes, ceramic boards, metal plate and resin-made circuit boards and particularly, to adhesive tapes suitable for use in wire-bonded semiconductor devices. This invention is also concerned with semiconductor devices fabricated using such adhesive tapes.
2) Description of the Related Art
As is shown in FIG. 11, a semiconductor device has heretofore been fabricated by fixing a semiconductor chip 7 on a die pad 9a of a leadframe with an adhesive 10 and then wire-bonding the semiconductor chip 7 and lead pins 9b of the leadframe with gold wires 8. Along with the gold wires, the semiconductor chip thus wire-bonded is sealed with a resin.
Reflecting the ever-increasing volume of information in recent years, there is now an increasing demand for the inclusion of much more lead pins in leadframes for such semiconductor devices. On the other hand, there is another increasing demand for smaller semiconductor chips in view of the recent trend toward a higher mounting density and a lower fabrication cost. As a result, lead pins tend to become longer and accordingly, to have a smaller width and narrower intervals These lead pins are therefore required to have high accuracy at tips of inner leads.
Upon formation of a leadframe, there is however a limitation to the accuracy of its etching so that the above requirement can by no means be fulfilled. In the conventional techniques, positioning of a small chip and tips of inner leads of lead pins of a multi-pin leadframe at locations close enough to permit wire bonding leads to the problem that the tips of inner leads of the lead pins are brought into contact to one another or no leads can be formed because of the limited accuracy of etching or punching of the leadframe. To overcome this problem, it is necessary to widen the distance between the small chip and each of the tips of inner leads of the lead pins. This however results in longer distances between the semiconductor chip and the proximal tips of the individual lead pins, thereby developing the problem that gold wires connecting the semiconductor chip and the lead pins are brought into contact due to movement of the wires upon sealing the semiconductor chip and wires with a resin.